| In order to understand and promote effective teacher learning,there have been shifts of theoretical perspectives in language teacher learning research over the decades.Complex Dynamic Systems Theory(CDST)promises to offer new frames for the process and nature of teacher learning.Taking the CDST approach,this longitudinal case study aimed at understanding three high school EFL teachers’professional learning through doing research over 18 months.By collecting data of different sources,including interviews,observations,reflective journals,and artifacts,the study described how teachers’ cognition changed and then analyzed the complexity,dynamics and systemacity underlying the changing process.The study had the following findings.First,three teachers more or less changed their English teaching cognition and practice through professional learning activities and disparate developmental trajectories of the three teachers’ cognitive system were identified.Specifically,the three teachers’ cognitive systems experienced several perturbations and thereafter self-organizing changes.Two of them experienced adjustments and realignments,showing a potential,qualitative change;while one teacher’s cognitive system tended to stabilize after some adjustments.Second,perturbations served as the catalyst to teachers’ cognitive change as perturbations possibly led to dissonance or disequilibrium in teachers’ cognitive system.Typical perturbation events included writing and revising research proposals,communicating with mentors,receiving comments and feedback from university researchers,etc.Third,opportunities and conditions for learning were shaped by the interactions within teachers’ own cognitive system and other systems(e.g.teacher professional development program,classrooms,schools).As learning unfolded,the components and their relationships of systems changed;the interactions and combinations of the components created affordances or constraints for learning.For example,the negative effect of prior experience and teacher identity,inadequate teacher knowledge and constraining institutional culture may hinder learning;interactions between theoretical knowledge,practical experience and teacher reflection would support teacher earnings;moreover,the intensity and density of perturbations have huge impact on the possibilities of teacher learning.Fourth,teachers’ agency,which includes professional development motivation,identity and reflexivity,was interwoven with system interactions and had an immediate effect on teacher learning.This study has important theoretical significance for language teacher learning and professional development research.First,this study gave an account of teacher learning by analyzing the interactive relationships between systems and deepened the understanding of the nature of teacher learning.Second,this study concretized the key terms(e.g.perturbation,emergence)of CDST,which enhanced the applicability and feasibility of using CDST in empirical studies.Third,this study used CDST to study Chinese EFL teachers and explore local contexts and problems,which will help promote the theoretical innovation of Chinese foreign language teacher education.Moreover,this study has practical implications for language teacher professional development.In order to create optimal conditions for effective teacher learning,teacher professional development should follow these principles.First,the teacher learning system should involve diverse components which should be interactive with each other.Teacher training program should incorporate multiple agents,utilizing interactions among systems,among different agents to create learning opportunities.Second,teacher professional development should create perturbations so as to cause dissonance to teachers’ cognition.To achieve this effect,professional development activities should be high-order,challenging and transformative,while the teacher educators(or trainer)should act as one who urges,critiques and perturbs,so as to help teachers break the inertia of cognition and practice.Third,sustained and recursive learning activities should be designed and implemented.Such learning activities should be able to engage teachers in the recursive cycle of "learning(inquiry)-reflection-enactment" and make teachers’ non-linear change possible.Fourth,professional development should value and cultivate teacher agency,help teachers become self-regulated,autonomous and critical learners. |